win32mbcs: also wrap windows.pconvert()

Use os.path.split() for MBCS with win32mbcs extension.

win32mbcs: look up modules using sys.modules (issue1729) globals()[module] doesn't work for modules inside of packages, such as os.path.

fix memory usage of revlog caches by limiting cache size [issue1639]

keyword: eliminate potential reference cycles from kwrepo - delete kwrepo.commitctx after using the tweaked version - prefer self.hook over repo.hook to avoid nesting Also pass arguments to commit as arbitrary list. Thanks to Simon Heimberg and Matt Mackall for guidance.

convert/cvs: improve error message on unexpected server output.

transaction: fix uncaught ENOENT (issue1724) The opener raises an IOError on errors where transaction expects an OSError.

branch heads: fix regression introduced in e67e5b60e55f (issue1726) For merge nodes it is not adequate to only check a single possible branch head for whether it is an ancestor of the latest head, but it needs to be done for each possible branch head.

subrepo: use hg.repository instead of creating localrepo directly this way, extensions' reposetup will be called, which allows for git subrepos to be handled by hg-git (and I believe the same goes for svn and hgsubversion)

ignore: separate pattern extraction from match compilation hgignore files have slightly different syntax from match objects, e.g. syntax: foo headers, regexp: forms, and re being relre. Put conversion from hgignore syntax into match syntax into a standalone function so that it is easier to validate hgignore hunks externally.